#include <bits/stdc++.h>
using namespace std;

#define pb push_back
#define mp make_pair
#define dbg(x) cout << #x <<": " << x << "\n";
using ll = long long;

const string myf = "darb";
ifstream fin(myf + ".in");
ofstream fout(myf + ".out");


int n, x, y, ans;
int dp[100005];
vector<int> g[100005];

void dfs(int x, int last) {
	int max1, max2;
	max1 = max2 = 0;
	for (auto i : g[x])
		if (i != last) {
			dfs(i, x);
			if (max1 < dp[i])
				max2 = max1, max1 = dp[i];
			else if (max2 < dp[i])
				max2 = dp[i];
		}
	dp[x] = max1 + 1;
	ans = max(ans, max1 + max2 + 1);
}
int main() {

	fin >> n;
	for (int i = 1; i <= n; ++i) {
		fin >> x >> y;
		g[x].pb(y);
		g[y].pb(x);
	}

	dfs(1, 0);
	fout << ans << '\n';

	fin.close();
	fout.close();
	return 0;
}